package src.com.java.dtgh.oneDay;

public class demo7 {

    public int numTrees(int n) {

        int[] dp = new int[n + 1];
        dp[0] = 1;

        for(int i = 1;i <= n;i ++){
            for(int j = 1;j <= i;j++){
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }

        return dp[n + 1];
    }
}
